DESCRIPTION: The Cooperative Family Registry for Breast Cancer Studies (CFRBCS) was initiated by the National Cancer Institute (NCI) to provide a resource for multidisciplinary studies of breast and ovarian cancer. The 6 participating sites have accumulated a large computerized data base with genetic and environmental risk information from an ethnically diverse set of families with a history of breast and/or ovarian cancer. Plasma and DNA are available for all participants, and tumor specimens have been obtained from those with a diagnosis of breast/ovarian cancer. The combined resources available in the CFRBCS have already begun to create unprecedented research opportunities for the genetic community. The identification of the family as the unit of study in cancer research provides an exceptional opportunity to explore the multifactorial contribution of genetic, environmental and lifestyle factors associated with the risk of cancer. The recognition of a familial risk for cancer, however, has vast personal, medical, social and ethical implications for those involved. The fast pace of discovery in the area of cancer genetics must be accompanied by a shift in paradigms to identify the family, rather than the individual, as the unit of cancer risk, to examine the impact of risk information on family dynamics, and to develop novel mechanisms of risk communication within families to maximize the preventive potential of the new science. The CFRBCS has a unique opportunity to engage study families in a partnership to explore sociocultural differences in the behavioral and social issues faced by individuals and their families as they formulate relevant perceptions of their risk for cancer and as they attempt to communicate risk information within the family. The proposed study will first explore the determinants of individual and familial participation in a breast cancer registry with both a retrospective approach to characterize the families recruited to date and a prospective approach applied to the proposed effort to extend recruitment of families. It will then examine the dynamics of familial communication patterns as they relate to cancer risk information, and the impact of registry participation on health-related behaviors among family members.